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PatchSiren cyber security CVE debrief

CVE-2026-20217 Cisco CVE debrief

CVE-2026-20217 is a vulnerability in ClamAV's PESpin file format parser. This vulnerability could allow an unauthenticated, remote attacker to cause a DoS condition or possibly other expanded impacts due to memory corruption on an affected device. The vulnerability is caused by improper boundary checks for content in PESpin files during scanning, which may result in an out-of-bounds buffer write. An attacker could exploit this vulnerability by submitting a crafted file that contains PESpin content to be scanned by ClamAV on an affected device. A successful exploit could allow the attacker to cause the ClamAV scanning process to terminate, resulting in a DoS condition on the affected software.

Vendor
Cisco
Product
Secure Endpoint
CVSS
HIGH 7.5
CISA KEV
Not listed in stored evidence
Original CVE published
2026-07-01
Original CVE updated
2026-07-09
Advisory published
2026-07-01
Advisory updated
2026-07-09

Who should care

Users of Cisco Secure Endpoint and ClamAV should be aware of this vulnerability and take necessary steps to mitigate it. This includes administrators of systems that use ClamAV for scanning files, especially those using Cisco Secure Endpoint on macOS, Linux, and Windows platforms.

Technical summary

The vulnerability in ClamAV's PESpin file format parser can lead to memory corruption and potentially allow an attacker to cause a DoS condition. The issue arises from inadequate boundary checks during the scanning of PESpin files, which can result in an out-of-bounds buffer write. This vulnerability can be exploited by submitting a specially crafted PESpin file to be scanned by ClamAV on an affected device, potentially causing the scanning process to terminate and leading to a DoS condition.

Defensive priority

High

Recommended defensive actions

  • Apply patches or updates provided by Cisco to fix the vulnerability in ClamAV's PESpin file format parser.
  • Implement compensating controls such as monitoring for suspicious file scanning activities.
  • Conduct regular inventory checks to ensure all systems using ClamAV and Cisco Secure Endpoint are identified and patched.
  • Restrict access to systems that use ClamAV to prevent exploitation.
  • Monitor ClamAV scanning processes for abnormal terminations.

Evidence notes

The CVE record was published on 2026-07-01T17:16:30.130Z and was last modified on 2026-07-09T18:07:46.497Z. The NVD entry is currently Analyzed. Cisco has provided a vendor advisory for this vulnerability.

Official resources

AI-assisted PatchSiren debrief based on the supplied source corpus. The CVE record was published on 2026-07-01T17:16:30.130Z and has not been modified since then. The NVD entry is currently Analyzed.